Explanation:
How far can you see?
The
Andromeda Galaxy 2.5 million light years away is the most distant
object easily seen by the unaided eye.
Other apparent denizens of the night sky, stars, clusters, and nebulae,
typically range from a few hundred to a few thousand light-years
away and lie well within
our own Milky Way Galaxy.
Also known as M31, the
Andromeda
Galaxy is the faint smudge near top center of this Earth and skyscape,
taken from eastern Italy, near Monte Conero on the Adriatic sea coast.
From a few centimeters
to a few million light-years,
the picture demonstrates a stunning range of vision.
Though galaxy and
seaside rocks could be seen with the eye on that
clear summer night, no camera captured this view in a single exposure.
Because the stars trailed
above the horizon while the picture was made,
separate exposures tracking the stars were combined
with one of rocks and cliffs made with the camera steadied
to create the tantalizing scene.